What do the following two equations represent? $-5x+4y = -1$ $-8x-10y = 5$
Solution: Putting the first equation in $y = mx + b$ form gives: $-5x+4y = -1$ $4y = 5x-1$ $y = \dfrac{5}{4}x - \dfrac{1}{4}$ Putting the second equation in $y = mx + b$ form gives: $-8x-10y = 5$ $-10y = 8x+5$ $y = -\dfrac{4}{5}x - \dfrac{1}{2}$ The slopes are negative inverses of each other, so the lines are perpendicular.